The Relationships between "S" Shape Deformation Characteristics of Tan-Lu Fault Zone and the Differences of Hydrocarbon Accumulation in Liaodong Bay
Huang, Xiaobo; Xu, Changgui; Zhou, Xinhuai; Wei, Gang; Zhang, Zhongqiao; Chai, Yongbo
In the Cenozoic Era, the Tan-Lu fault zone was mainly represented as multiple dextral strike-slip faults which extend 20 to 40 kilometers and follow a southwest to northeast trend, in Liaodong Bay. These faults mainly distributed in the west side of Liaoxi uplift, the central of Liaozhong sag, and both sides of Liaodong uplift. It has been proved that the accumulation and distribution of hydrocarbon which occurred in the Cenozoic Era were mainly controlled by these large-scale strike-slip faults in Liaodong Bay. Three-Dimensional (3-D) seismic data shows that the Tan-Lu fault zone was not like a straight lined extension, but rather a continuous "S" shape curved extension. The "S" shape curved bends of the strike-slip faults can be classified as "left convex type" and "right convex type" by planar features.
Based on 3-D seismic interpretation, the "S" shape curved bends of the Tan-Lu fault zone were found to be mainly restrained in the compressional tectonic stress fields in Liaodong Bay. As a result, many semi-anticlinal traps tend to form in the area. These traps usually range from five to 20 square kilometers and are the ideal targets for hydrocarbon exploration. However, in the areas that are far away from the "S" shape curved bends, it is difficult to form structural traps because of the extensional tectonic stress fields, but it tends to form many long-term activated strike-slip adjustment faults which may provide good vertical conduits for the oil and gas migration.
The discoveries of several oil and gas fields have proven that the hydrocarbon accumulation was mainly affected by the "S" shape curved bends of Tan-Lu fault zone, in Liaodong Bay. The characteristics of hydrocarbon accumulation were obviously different from each other in the area. There are four types of hydrocarbon accumulation models in Tan-Lu fault zone, in Liaodong Bay. The first one is "right convex enriched, left convex poor" on the left part of the fault zones, the second one is "right convex poor, left convex enriched" on the right part of the fault zones, the third one is "hanging wall enriched, footwall poor" on the fault zones, and the fourth one is "footwall enriched, hanging wall poor" on the fault zones.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013